Method and installation for hot-rolling strips using a Steckel rolling frame

ABSTRACT

The invention relates to a method and an installation for hot-rolling strips using a reversible Steckel rolling frame ( 8 ), each side of which is equipped with a respective furnace coiler ( 9, 10 ) and a driving mechanism ( 17,18 ), provided between the furnace coiler ( 9, 10 ) and Steckel rolling frame ( 8 ). The aim of the invention is to crop particularly thin, hot strips. To achieve this, the strip is cropped during the reversible rolling process by a single pair of flying cropping shears ( 20 ), positioned between one of the driving mechanisms ( 17 ) and the Steckel rolling frame ( 8 ). The cropping shears comprise in particular a drum blade.

The invention concerns a method and an installation for hot rollingstrip, especially steel strip, in which the rolling stock is rolled in areversing Steckel rolling stand and is conveyed by drivers between twofurnace reels, which are arranged on either side of the Steckel rollingstand in the direction of conveyance. The drivers are arranged betweenthe corresponding furnace reel and the Steckel rolling stand.

An installation with a Steckel rolling stand is described, for example,in DE 195 49 208 A1. In accordance with the prior art, the rolling stockis rolled in at least one reversing roughing stand in a number ofbreakdown passes to produce a prestrip, which is then conveyed to aSteckel finishing stand via an intermediate roller table. In the Steckelfinishing stand, the strip is finish-rolled in a number of passes toproduce finished strip of a predetermined gage. The strip is thencooled, possibly by forced cooling, coiled in a finished-strip coiler,and removed for further processing.

A cropping shear, which is assigned to the breakdown train, is installedbetween the roughing stand or the roller table and the finishing stand.The irregular trailing and leading ends of the prestrip that were formedduring the breakdown rolling are separated by this cropping shear. Thestrip, which has been cropped immediately after the breakdown train, isthen further reduced in the Steckel rolling stand.

This rolling process again results in the formation of irregular stripends or slivers, which interfere with threading in the coiling processin the furnace reel. Especially in the case of strips that have beenrolled very thin, so that severe, unfavorable strip sliver formation hasoccurred, these irregular strip ends have a negative effect on thecoiling process. With conventional Steckel rolling stands, correction ofthe strip ends during the rolling operation is not possible in the areaof the finishing stand.

EP 0 088 201 B1 describes a reversing rolling mill with two reels, inwhich a cropping shear is installed after a second finishing stand andthe reversing reel. The cropping shear comprises an upper and a lowercutter block, which are driven at a peripheral speed that is adjusted tothe running speed of the rolling stock, so that the blades are movedtogether with the rolling stock during the cutting. A support roller forthe hot strip is rotatably supported on the lower cutter block, so thatin the area of the cropping shear, guidance for the hot strip isequivalent to the guidance on the roller table. If the cutter blocks aredriven for a cropping operation, the support roller is rotated down andaway from the vicinity of the hot strip by rotation of the cutter blockabout its axis in order to make room for the blade action. After a fullrotation of the cutter block, the support roller arrives back in itsoperating position. The functions of cutting and supporting are thusobtained by rotation of the cutter block about the cutter block axis.The reversing reels are not furnace reels.

EP 0 593 398 A1 describes a Steckel rolling stand for hot rolling, inwhich a unit comprising a driver and a cropping shear is arrangedbetween two reel furnaces and a rolling stand. The cropping shearcomprises nonrotating upper and lower shear blades. The shear can cutoff (crop) the ends of the strip only when the rolling stock isstationary. The necessary stoppage time has an unfavorable effect on thestrip temperature that is necessary to produce thin strip gages.

Proceeding on the basis of this prior art, the objective of theinvention is to develop a method and an installation of this generaltype with which especially thin, hot strip can be cropped without anyproblems and without loss of time.

This objective is achieved by the method according to Claim 1 and theinstallation according to Claim 3. Advantageous modifications aredescribed in the dependent claims.

The central idea of the invention is that the strip is cropped duringthe reversing rolling in the Steckel rolling stand by means of a singleflying cropping shear installed between a driver and the Steckel rollingstand. The flying corrective cropping is made possible in the vicinityof a Steckel rolling mill with only a single shear. This has theadvantage that the irregular strip ends or slivers that form especiallyin the case of thin strip gages can be removed within the rollingprocess, so that the coiling process in the furnace reels or during thefinal coiling is not disturbed.

Since the cropping shear is integrated in the reversing process of theSteckel rolling, a single shear can be used for cropping in both striprunning directions. In particular, if final strip gages of less thanabout 2 mm are being rolled, the given end of the strip that is enteringthe furnace reel or that is running in the direction of this furnacereel and the driver located in front of it is cropped by the integratedcropping shear, so that the process can run smoothly and withoutdisruptions in the furnace reel.

The cropping shear itself is a flying shear, so that cropping can beperformed during rolling with the rolling speed largely maintained. Dueto the flying cutting, there is almost no loss of time during cutting,so that the strip undergoes very little cooling, i.e., favorable striptemperatures are maintained.

Since the proposed cropping shear is used in the vicinity of the Steckelrolling stand and thus is used to cut strip that is already relativelythin, one shear of a small size compared to the previously known shearin the breakdown rolling train is sufficient. Since the disturbing stripends form only after several reversing passes in the Steckel finishingstand, the shear can be designed for cutting small strip thicknesses,i.e., it can be designed for relatively light-duty work.

In addition to a process sequence of the type described in DE 195 49 208A1, an installation with a Steckel rolling stand and integrated croppingshear between a furnace reel and the rolls of the driver can also beused in other, alternative process sequences, e.g., of the typesdescribed in DE 40 09 860 C2. The process sequence described therecomprises a CSP (compact strip production) continuous casting plant witha downstream soaking furnace, in which strip-like feed material inprestrip lengths is subjected to temperature homogenization or heatingto rolling temperature. A shear and a rolling mill are arrangeddownstream of the soaking furnace in the direction of strip conveyance.The rolling mill consists of a reversing Steckel stand or a tandemfinishing train. The aforementioned shear in this process sequenceserves to break up nonrollable material and does not operate as acropping shear.

The use of a Steckel rolling stand as a finishing mill in this processsequence is advantageous due to the low capital costs, and especially inthis case, the flying cropping shear in the vicinity of the Steckelrolling stand offers a good possibility for correcting the irregularstrip ends that arise during the rolling process and for avoidingdisturbances of the coiling process in the furnace reels.

In accordance with an especially preferred modification, the croppingshear, which is installed between one of the drivers and the Steckelrolling stand, is designed as a drum blade cropping shear with both anupper and a lower adjustable blade drum for the flying cutting of thestrip material, such that each blade drum and especially both bladedrums can be adjusted between a position some distance from the passingstrip material during the rolling operation and a cutting position.

A shear of this type is installed in the process path between theSteckel rolling stand and a furnace reel or coiling furnace. Both bladedrums are located during the rolling operation in a retracted positionwith a good distance between the blade drum and the strip and arebrought into the cutting position only to make a cut. In this way, theblade drums are not arranged so close to the hot strip when they are inthe rolling position. Therefore, the thermal stress on the blade drumsis significantly reduced.

Due to the large distance of the blade drum from the strip, defectivestrips, for example, strips with a turn-up or turn-down or withwaviness, can pass unhindered through the shear. Damage to the upperside or underside of the strip by contact with the blade drums iseffectively prevented.

In addition, in accordance with a preferred embodiment, due to thedistance of the blade drums from the strip, they can continuouslyrotate, so that the thermal stress is uniformly distributed over thecircumference of the drum.

Even if the blade drums do not continuously rotate, before the cut ismade, they are set in motion at the proper time and synchronized withthe strip running speed. The shear drive power can be kept low in thisway. It is not necessary to accelerate the blade drums to the striprunning speed within a small angle of rotation (which is usually180–270°), which is associated with high motor power.

In accordance with a preferred embodiment, heat shields are swung intothe space between the adjustable blade drums and the strip during therolling operation. This measure further reduces the thermal stress onthe blade drums.

It is advantageous for the lower heat shield to be equipped with one ormore support rollers, so that the strip receives rolling support as itpasses through during the rolling operation. Each support roller on thelower heat shield has a stable construction and is preferably driven, sothat the underside of the supported strip is not damaged as is passesthrough. This support roller can be externally driven, i.e., fromoutside the shear housing, by a universal-joint shaft. The heat shields,which are subject to high wear due to the high heat load between theblade drums, are preferably designed to be easily replaceable. They arereplaced, for example, as part of a blade change.

In accordance with a modification of the installation, the blade drumsare cooled from the outside with a coolant, such as water. In this case,the upper heat shield serves as a water collection channel, so that thecooling water for the upper blade drum does not come into contact withthe strip and unnecessarily lower the strip temperature. Permanentcooling of the blade drums during the passage of the strip through theshear is possible.

Each swiveling heat shield is preferably supported on the axis of thecorresponding blade drum. Since the heat shields are not subject toexcessive mechanical loads, large bearings of low load-bearing capacityare sufficient for adaptation to the journal diameter of the bladedrums.

In addition to the bearing of the heat shields on the blade drumjournals, it is also possible to mount them rotatably on the shear frameor the extended guide levers for the blade drums.

The claimed adjustment of the blade drums is preferably accomplished byan upper and a lower toggle mechanism, which, in accordance with amodification, are combined in a closed shear frame. The shear frameabsorbs the cutting force and at the same time serves as the stop forthe coupling of the blade drums in guide levers.

In its extended position, the toggle mechanism guarantees adimensionally stable, precise position of the blade drums for the cut.Relatively small forces are needed for the adjustment, because only theblade drums have to be moved. The cutting force arises only in the endposition of the toggle link. The end position is reached shortly beforethe shear blades make contact with the strip material.

The swinging away of the heat shields before the cut is made can beaccomplished by the toggle drive itself and is thus automatic. It isalso possible to use separate hydraulic cylinders, which allow moreaccurately controlled actuation with respect to time. Furthermore,hydraulic actuation offers the advantage of swiveling the heat shieldsto both sides, so that a feed funnel always faces the entering end ofthe strip.

In addition, the installation is modified by a special roller table,which consists of two swiveling roller tables or units, which arearranged at the inlet and outlet of the shear for conveying the strip.Depending on the strip running direction, the roller table unit locatedafter the blade drums is swung upward in such a way that the cut cropend can fall freely and can be removed without any problems. As soon asthis has been accomplished, the roller table unit is swung further inthe same swiveling direction, until it again reaches its horizontalposition. When this swiveling operation has been completed, the nextcropped strip end can be caught and carried away.

It is advisable for the rollers of the swiveling roller table units tobe independently driven to avoid damage of the underside of the strip.The roller drive can be initiated by means of the swivel bearing of eachunit. The distribution of the drive can be accomplished by chain drivesor spur gears with intermediate gears. A hydraulic motor or an electricmotor with intermediate gears can be used for the swivel drive of theroller table or roller table units.

As a variant for the swiveling roller tables, it is also possible to usestiffened, rotating guide plates with the same function with respect tothe removal of crop ends or the collection of the cropped ends of thestrip.

The invention has the advantage that the irregular strip ends or sliversthat form at both the leading end and the trailing end of a strip,especially in the case of thin strip gages, can be removed within therolling process, and the coiling process in the furnace reels or duringthe final coiling is not disturbed. The irregular strip ends (leadingend, trailing end of strip) can be corrected during the rollingoperation by crop cuts by means of the flying cropping shear in such away that the strip ends satisfactorily thread into the typical furnacereels for the Steckel rolling process, especially into the receivingslot of the reel drums.

The invention includes the use of multiple-stand Steckel rolling stands.

Additional details, features and advantages of the invention areapparent from the following explanation of the specific embodimentillustrated in the drawings.

FIG. 1 shows a schematic drawing of a Steckel rolling stand with acropping shear between a driver and the Steckel rolling stand.

FIG. 2 shows a schematic drawing of a conventional installation with aroughing stand that is followed by a cropping shear and a Steckelrolling stand.

FIG. 3 shows a schematic representation of a drum blade cropping shearwith adjustable upper and lower blade drums with a first embodiment of atoggle drive.

FIG. 4 shows a cropping shear in accordance with FIG. 3 with a secondembodiment of the toggle drive.

FIG. 5 shows a cropping shear in accordance with FIG. 3 with a thirdembodiment of the toggle drive.

FIG. 6 shows a cropping shear in accordance with FIG. 3 with a fourthembodiment of the toggle drive.

FIG. 7 shows a cropping shear with the blade drum heat shields driven bythe toggle mechanism.

FIG. 8 shows a cropping shear with a hydraulic swivel drive for the heatshields.

FIG. 9 shows a cropping shear with the swiveled swiveling roller tableon the left side.

FIG. 10 shows a cropping shear with the swiveled swiveling roller tableon the right side.

The conventional installation for hot rolling strip that is shown inFIG. 2 comprises at least one reversing roughing stand 1 for thebreakdown rolling of a prestrip and at least one Steckel finishing stand2 for reducing the prestrip to the finished strip. The two parts (1, 2)of the installation are joined by an intermediate roller table 3. TheSteckel finishing stand 2, which is a four-high reversing stand in theillustrated case, comprises two reel furnaces 4, 5, in which the stripis coiled and at the same time maintained at rolling temperature. Afterthe finishing rolling has been completed, the strip passes through afinal unit 6, which in the present case consists of a cooling line 6 a,for example, a laminar cooling line, and another coiler 6 b. The stripis wound into a coil, so that it can be conveyed for further processing,for example, in a cold-rolling mill or a coating station, or forshipment out of the plant. A cropping shear 7 for cropping the prestripis installed in front of the Steckel finishing stand 2 with respect tothe direction of strip conveyance (arrow). The cropping shear 7 isdesigned according to the gage of the prestrip, which can be on theorder of 30 mm, and is of a suitable size for the required cuttingeffect on the strip.

FIG. 1 shows a single-stand Steckel rolling stand 8, which can beintegrated in a process sequence of the type shown in FIG. 2 or can beintegrated in a different type of process sequence. The Steckel rollingstand 8 in this case is also a four-high reversing stand. The inventionalso includes the use of multiple-stand Steckel rolling mills. In thedirection of production progress (see arrow direction) one furnace reel9, 10 each is installed before and after the reversing Steckel stand 8.A furnace reel 9, 10 comprises a furnace with a furnace shell 11, 12 anda coiler 13, 14 for winding the rolled strip onto the coil and unwindingit from the coil. The broken line 15, 16 indicates the circumference ofa wound coil. Two drivers 17, 18, each with two driving rolls, arearranged on either side of the Steckel stand 8 between each furnace reel9, 10 and the Steckel stand 8, i.e., one driver each is installed on thefeed side and the delivery side of the finishing stand. The furnace reelthat is unwinding or inactive is closed, and the furnace reel that iswinding is opened by the furnace guide 19 a, 19 b arranged on thefurnace reel 9, 10, respectively. A single cropping shear 20, which isdesigned small compared to previous prestrip cropping shears (see 7 inFIG. 2), is installed on the feed side of the Steckel rolling mill 8between one of the drivers (in the present case, for example, driver 17)and the Steckel rolling stand 8. The crop ends can be removed by asuitable collecting device.

This shear crops the front and rear ends of the strip during the rollingprocess, i.e., without any significant idle times of the hot strip andthus without the strip temperature losses associated with idle time,which interfere with the achievement of thin strip thicknesses of about2 mm or less.

The use of the shear 20 is described below with reference to the otherdrawings, which show a drum blade cropping shear and will be explainedmore explicitly later. The strip runs, for example, after severalrolling passes, out of the reversing Steckel stand 8 in the direction ofthe furnace reel 9. The development or shape of the strip end (sliver)makes a cropping cut necessary in order to carry out the threading andcoiling process in the furnace reel without any trouble. For thispurpose, the cropping shear is activated, i.e., the blade drums 28 a, b(FIGS. 3–6), are brought together, and their speed of rotation isadjusted to the given strip rolling speed.

The device for removing the crop ends, in this case, the swivelingroller table (FIG. 9) 42, is adjusted. The closed-loop control systemfor the strip flow and the shape of the strip end brings together theblade position of the rotating blade drums and the intended cuttingpoint on the strip end. The cropping cut is then made. The blade drums28 a, b (FIGS. 3–6) are then moved apart again, and the cropped strip isguided to the driver 17 and, without stopping, into the furnace reel 9by means of the completely swiveled roller table 42 (FIG. 9). In thefurnace reel 9, the rolled strip is wound until the trailing end of thestrip has nearly reached the position of the driver.

The rolled strip briefly comes to a stop and is ready for the followingrolling pass in the opposite, i.e., the reverse, direction.

At this time, the blade drums 28 a, b (FIGS. 3–6) of the shear 20 havealready been brought together again and are rotating in the oppositedirection from before. The swiveling roller table 43 (FIG. 10) isadjusted. Once again, the blade drum rotation and the blade position aresynchronized with the cutting point at the end of the strip under thecontrol of the closed-loop control system for the strip flow and theshape of the strip end. The cropping cut at the strip end is made, andthe crop end is removed. The cropped strip is conveyed by the rollertable 43 (FIG. 10) in the direction of the Steckel reversing stand, inwhich it is further rolled.

To make the conveyance of the strip on the stand roller table 21 a, 21 bin the vicinity of the Steckel rolling stand 8 more uniform, lateralguides 22 a, b are provided, which are not limited to the extent shownin the drawing. On the side opposite the cropping shear 20, a stripmeasuring device 23 is installed between the Steckel rolling stand 8 andthe second driver 18. This device 23 can be integrated in a closed-loopcontrol system for automatically controlling the Steckel rolling stand 8and the roll gap. In addition, the values acquired by this device 23provide information about the state of the head of the strip and thestrip end, which can be incorporated in the automatic control of thecropping shear 20 in order, for example, to activate the flying croppingshear according to the necessary crop lengths.

Each of FIGS. 3 to 6 shows a drum blade cropping shear 20 with upper andlower blade drums 28 a, b, which can be adjusted by means of an upperand lower toggle mechanism 24 a, b, 25 a, b, 26 a, b and 27 a, b,respectively. FIGS. 3 to 6 shows four different embodiments of drives 29a–d of the toggle mechanisms for adjusting the blade drums 28 a, b.However, the invention is not limited to these four embodiments. Acommon feature of all four embodiments is that the toggle mechanisms aredriven from one side of the shear or, in the case of the embodimentshown in FIG. 6, from the top and bottom. The driving torque istransmitted to the toggle mechanism on the other side of the shear orthe other side of the blade drum by a suitably dimensioned synchronousshaft 30 a, b. It should be noted that the drawings show only theprinciple of the different variants of the shear. The mechanicaladvantages and the necessary angular position changes resulting fromthem are not shown correctly.

In particular, FIG. 3 shows a shear frame 32 with an upper and lowerblade drum 28 a, b with an upper and lower blade 33 a, b mounted onthem. The strip is guided between the blade drums 28 a, b by a rollertable 34. The driving torque of the respective toggle mechanisms 24 a,b, which is produced by a hydraulically operated connecting rod 35, istransmitted to the other side of the shear by an upper and lowersynchronous shaft 30 a, b. The toggle mechanisms 24 a, b consist oftoggle links 36 a, b connected with the synchronous shafts 30 a, b,connecting rods 37, additional levers 38–39 and guide levers 40.

In contrast to this, the drives 29 b, c and d shown in FIGS. 4, 5 and 6have two noninteracting drive units. In the embodiment shown in FIG. 6,the drive is realized by two hydraulic swivel drives (29 d), each ofwhich acts on a synchronous shaft 30 a, b between the two sides of theshear and effects the adjustment of the upper and lower blade drums 28a, b by the toggle links.

FIGS. 7 to 10 show the design of the cropping shear with heat shields 41a, b and their swivel drive and the arrangement and function of a novelroller table (42, 43).

The heat shields 41 a, b are supported on the axis of the blade drums 28a, b and are shown in the drawings in the position in which they areswung in, i.e., in their position during the rolling operation. In theembodiment shown in FIG. 7, a lever 44 a, b of the toggle mechanism 24 a[sic—24 a, b] engages the end 45 a, b of the heat shield 41 a, b that isdirected away from the strip, so that the heat shield 41 a, b isswiveled by the drive of the toggle mechanism 24 a, b.

In the embodiment shown in FIG. 8, these drives are uncoupled. Twoseparate drive units 46 a, b in the form of hydraulic cylinders areprovided for swiveling the heat shields 41 a, b. In contrast to thesituation with the toggle mechanism 24 a, b, the heat shield 41 a, b canbe swiveled both left and right by the piston rod of the separate drivesystems 46 a, b to assist the threading of the strip.

To reduce harmful thermal stress of the blade drums 28 a, b,they arecooled from the outside with water. The cooling water is collected bythe curved, shape of the upper heat shield 41 a, which is concaveupward, i.e., towards the axis of the drum.

The lower heat shield 41 b has a preferably driven support roller 47,which prevents sagging of the strip as it passes through the shear 20.With the heat shield 41 b swung in, the support roller 47 and its driveare integrated in the roller table for the strip.

The roller table itself consists of two roller table units 42, 43, whichare arranged at the inlet and outlet of the shear frame 32. A rollertable unit 42, 43 of this type is designed as a swiveling roller tablethat is independent of the further roller table and has a central swivelbearing 48, 49. In the present embodiment is has four additionalrollers, although the invention is not limited to this number.

The manner of operation of the swiveling roller tables is explained withreference to FIGS. 9 and 10. For a strip that is being conveyed fromleft to right, whose end is being cropped, the swiveling roller table orthe roller table unit 42, which is located after the blade drums 28 a,b, is swung upward in the left direction from the horizontal in such away that the cut crop end can fall over the swiveled roller table andout of the shearing area. The swiveling roller table is then furtherswiveled all the way around in the left direction until it has againarrived in the horizontal position, as indicated by the rollers 50 shownin gray, so that the following strip leading end is again supported.FIG. 10 shows the position of the swiveling roller table or roller tableunit 43 during a cropping cut towards the rear (right). This is followedby a complete swiveling of the swiveling roller table, so that thefollowing strip leading end is again supported. The use of the swivelingroller tables or roller table units 42, 43 ensures that a crop end doesnot interfere with the strip material that subsequently starts to passthrough again but rather can be effectively removed from the rollertable.

LIST OF REFERENCE NUMBERS

-   1 reversing stand-   2 Steckel finishing stand-   3 intermediate roller table-   4 reel furnace-   5 reel furnace-   6 final unit, cooling line 6 a-   7 prestrip cropping shear-   8 Steckel rolling stand-   9 furnace reel-   10 furnace reel-   11 furnace shell-   12 furnace shell-   13 coiler-   14 coiler-   15 circumference of a coil-   16 circumference of a coil-   17 driver-   18 driver-   19 furnace guide-   20 cropping shear-   21 stand roller table (21 a, b)-   22 lateral guides (22 a, b)-   23 strip measuring device-   24 toggle mechanism-   25 toggle mechanism-   26 toggle mechanism-   27 toggle mechanism-   28 blade drums (28 a, b)-   29 drives (29 a–d)-   30 synchronous shafts (30 a, b)-   31 bearings (31 a, b)-   32 shear frame-   33 blade (33 a, b)-   34 roller table-   35 piston rod-   36 toggle link (36 a, b)-   37 lever-   38 lever-   39 lever-   40 lever-   41 heat shield (41 a, b)-   42 swiveling roller table unit-   43 swiveling roller table unit-   44 lever-   45 end of the heat shield-   46 separate drive unit-   47 support roller-   48 central swivel bearing-   49 central swivel bearing

1. Installation for hot rolling strip with a reversing Steckel rollingstand (8), on either side of which a furnace reel (9, 10) is arranged,with drivers (17, 18), which are installed between each furnace reel (9,10) and the Steckel rolling stand (8), and with a cropping shear,wherein a single flying cropping shear (20) is installed between onedriver (17) and the Steckel rolling stand (8), wherein the croppingshear (20) is a drum blade cropping shear with both an upper and loweradjustable blade drum (28 a, b) for making the flying cut of the stripmaterial, such that each blade drum (28 a, b) can be adjusted between aposition some distance from the strip material during the rollingoperation and a cutting position, wherein a heat shield (41 a, b) can beswung into the space between the strip material and the correspondingadjustable blade drum (28 a, b), which has been moved into its positionsome distance from the strip material.
 2. Installation in accordancewith claim 1, wherein the lower heat shield (41 b) of the lower bladedrum (28 b) is equipped with at least one strip support roller (47),which, when the heat shield (41 b) is swung into place, prevents saggingof the strip as it passes through the shear.
 3. Installation inaccordance with claim 1, wherein a cooling device is provided forcooling the blade drums with a coolant, and that the upper heat shield(41 a) of the upper blade drum (28 a) simultaneously serves as a coolantcollection channel and as protection for the strip material. 4.Installation in accordance with claim 1, wherein each swiveling heatshield (41 a, b) is supported on the axis of the corresponding bladedrum (28 a, b).
 5. Installation in accordance with claim 1, wherein theblade drums (28 a, b) can be swiveled between a swung-out rollingposition and an engaged cutting position by means of an upper and alower toggle mechanism (24–27 a, b).
 6. Installation in accordance withclaim 5, wherein the upper and lower toggle mechanisms (24–27 a, b) arecombined in a closed shear frame (32).
 7. Installation for hot rollingstrip with a reversing Steckel rolling stand (8), on either side ofwhich a furnace reel (9, 10) is arranged, with drivers (17, 18), whichare installed between each furnace reel (9, 10) and the Steckel rollingstand (8), and with a cropping shear, wherein a single flying croppingshear (20) is installed between one driver (17) and the Steckel rollingstand (8), wherein a roller table area, which is located immediatelyadjacent to the cropping shear (20) and serves to convey the stripmaterial through the shear, is formed by two independently swivelingroller table units (42, 43), wherein, to allow removal of the crop end,each roller table unit (42, 43) can be swiveled out of the horizontalposition in such a way that the crop end can fall freely, withouthindrance by the roller table unit (42, 43), and that the roller tableunit (42, 43) can then be swung further in the same swiveling direction,until it again reaches its horizontal position.